New versions of Firefox prepare for its biggest change ever

Summary: Today's launch of Firefox 47 means the E10S version, Firefox 48, has reached the beta stage. With Electrolysis, Firefox will finally be able to use two or more processes at once.... the main problem being that it breaks a lot of extensions

Mozilla released Firefox 47, with improved handling for streaming, HTML5 video and the VP9 codec. But the more interesting news is that Firefox 48 has now reached the beta release stage. Firefox 48 incorporates the long-awaited Electrolysis (E10S), which enables the user interface to be run in a separate process from the tabbed content.

Electrolysis will improve Firefox's performance and security, but it breaks a lot of extensions. However, Firefox will stage the release to minimize the problem. In a blog post, Asa Dotzler wrote:

"When we launch Firefox 48, approximately 1 percent of eligible Firefox users will get updated to E10S immediately. The 1 percent of release users should get us up to a population similar to what we have in Beta so we'll be able compare the two. About ten days after launch, we'll get another round of feedback and analysis related to the release users with and without E10S. Assuming all is well, we'll turn the knobs so that the rest of the eligible Firefox users get updated to E10S over the following weeks. If we run into issues, we can slow the roll-out, pause it, or even disable E10sS for those who got it. We have all the knobs."

Dotzler says: "E10S is the largest change we've ever made to Firefox and we hope you'll help us get through this with as few surprises as possible."With Electrolysis, Firefox can use child processes for content (tabs), media playback and legacy plug-ins. This is some way short of Google Chrome, which uses a different process for each tab. However, the result is that Chrome is a huge resource hog: Chrome uses roughly twice as much memory as Firefox on Windows and Linux.

Eric Rahm has run some browser tests with Electrolysis, and says: "Overall we see a 10-20 percent increase in memory usage for the 1 content process case (which is what we plan on shipping initially). This seems like a fair trade-off for potential security and performance benefits."
With 8 content processes, Rahm says: "we see roughly a doubling of memory usage on the TabsOpenSettled measurement. It's a bit worse on Windows, a bit better on OS X, but it's not 8 times worse."

Unfortunately, Electrolysis breaks a lot of attachments, which could previously assume that the UI and web content were using the same memory space. Later, Firefox will get a WebExtensions API, which Mozilla says is "similar to the Blink extension API" that Chrome uses.
Programmers and users are encouraged to log problems on the "are we e10s yet" page at Are your add-ons e10s compatible?

At the moment, 153 extensions are compatible, 84 have been shimmed to work, 108 are broken, and 535 untested. The compatible extensions include Adblock Plus, Video Downloadhelper, Firebug, Greasemonkey, Tab Mix Plus and uBlock Origin. However, some major extensions have reported bugs, including NoScript, Ghostery, DownThemAll, Web of Trust, Session Manager, and the Flash Video Downloader.

Seven of the 12 most popular extensions have problems. This is likely to be a deal-breaker for many users, including me. Firefox 48 is scheduled for release on August 2, so extension suppliers have a limited amount of time to fix problems